Modulation of lymphokine production by interferon

Pretreatments with relatively low (25-250 U/ml) concentrations of interferon (IFN) enhanced while 5000-10 000 U/ml concentrations of IFN inhibited leukocyte inhibitory factor (LIF) and migration inhibitory factor (MIF) production of concanavalin A (Con A) stimulated human leukocytes. The lymphokine regulatory activity of IFN correlated with the antiviral activity of IFN preparations regardless of their specific activity and it showed species specificity. Modulation of lymphokine production depended not only upon the amount of IFN used but also on the length of IFN pretreatment. Blocking of lymphokine production by high concentration of IFN could not be explained by the effect of IFN on cell viability.